Tailgate assembly for heavy duty off-road trucks

ABSTRACT

A tailgate assembly for a dump body is provided. The dump body has a pair of opposing sidewalls and an open rear end. The dump body is movable relative between a lowered transport position and a raised dump position. The tailgate assembly including a pair of opposing sidearms each of which is pivotally connected to a respective sidewall of the dump body and a center-rear portion supported between the sidearms. The sidearms and center-rear portion are movable between a closed position wherein the center-rear portion spans substantially between the opposing sidewalls of the dump body and encloses the open rear end of the dump body and an open position wherein the center-rear portion is positioned away from the open rear end of the dump body. Each of the sidearms includes an extended portion at an end thereof. The extended portions are curved inwardly toward each other in overlapping relation to at least a portion of the center-rear portion. The extended portions are also connected to the center-rear portion so that a portion of an inside surface of each of the extended portions abuts against a portion of the outside surface of the center-rear portion.

FIELD OF THE INVENTION

This invention relates to heavy-duty off-road trucks and, moreparticularly, to a tailgate assembly for these trucks.

BACKGROUND OF THE INVENTION

The dump bodies of heavy-duty, off-road trucks are often provided withtailgate assemblies in order to increase their load capacity. A tailgateassembly typically includes a pair of straight sidearms which arepivotally mounted to the sides of the dump body and between which acenter-rear portion is supported. When the tailgate assembly is in aclosed position, the center-rear portion closes off the rear end of thedump body. Thus, when the tailgate assembly is closed, the effectivevolumetric capacity of the dump body is increased as material isprevented from spilling out of the rear of the dump body. Such tailgateassemblies are subjected to a significant amount of punishment and thusmust have a strong and durable design. One way in which this isaccomplished is by welding reinforcing structures onto the sidearms andcenter-rear portion. As will be appreciated, however, this is a verytime-consuming process.

Another area of concern with respect to the strength of the tailgateassembly is the connections between the sidearms and the center-rearportion. There are two different ways in which the center-rear portionis connected to the sidearms. Specifically, according to a firstconnection method, each end of the center-rear portion butts up againstthe inside surface of a respective one of the sidearms. Typically, aflange is provided on each end of the center-rear portion which extendsalong the inside surface of the respective sidearm. The center-rearportion is secured at either end to the arms by bolts which extendthrough the respective sidearm and flange in a direction parallel to thecenter-rear portion and perpendicular to the sidearm. Alternatively, thecenter-rear portion is secured at either end to the sidearms by welding.

With the other connection method, the arrangement of the center-rearportion and the sidearms is reversed. In particular, the inside surfaceof the center-rear portion butts up against the ends of the sidearms. Aflange is provided on the end of each sidearm that extends along theinside surface of the center-rear portion. The center-rear portion issecured to the sidearms by bolts which extend through the center-rearportion and the flanges in a direction parallel to the sidearms andperpendicular to the center-rear portion or by welding this joint.

A significant drawback with both of these bolted, or in some caseswelded, connection arrangements is that the connections compromise thedurability of the tailgate assembly. Specifically, during loading of thedump body and when the truck is travelling up an incline, the loadmaterial frequently rolls or slides against the center-rear portion ofthe tailgate assembly, subjecting it to a significant amount ofpunishment. By virtue of their arrangement, the nuts and bolts used toconnect the center-rear portion to the sidearms or the welded joints areresponsible for transmitting the forces applied against the center-rearportion to the sidearms. Unfortunately, the nuts and bolts and/or thewelding of the connection are/is ill equipped to perform this task asthey have difficulty withstanding the forces involved. As a result, thecenter-rear portion is susceptible to becoming separated from thesidearms after repeated use necessitating costly repairs or evenreplacement.

Another drawback with the first connection arrangement is that it makesit difficult to compensate for any variations in width between thecenter-rear portion and the dump body. If the center-rear portion is notprecisely matched to the width of the dump body, shims must be used atthe connections between the center-rear portion and the sidearms.Fabricating and assembling these shims, can make the assembly processsignificantly more time consuming and difficult.

Moreover, as a result of the need to use flanges on the ends of eitherthe sidearms or center-rear portion, it can be difficult to fit thebottom edge of the center-rear portion tightly against the rear end ofthe floor of the dump body when using the conventional connectionarrangements while still providing the needed clearance for operation ofthe tailgate. Thus, a gap frequently exists between the bottom edge ofthe center-rear portion and the rear end of the floor of the dump bodythrough which the load material can spill.

OBJECTS OF THE INVENTION

Accordingly, in view of the foregoing, a general object of the presentinvention is to provide a tailgate assembly for a heavy-duty, off-roadtruck which is stronger and more durable than tailgate assemblies thatare presently commercially available.

Another object of one embodiment of the present invention is to providea tailgate assembly for a heavy-duty, off-road truck which can bereadily adjusted to compensate for variations in width between thecenter-rear portion and the dump body and which provides a tight fitbetween the bottom edge of the center-rear portion and the rear of thedump body floor.

Another object of one embodiment of the present invention is to providea tailgate assembly for a heavy-duty, off-road truck which is lesstime-consuming to manufacture and easier to assemble to a dump body.

These and other features and advantages of the invention will be morereadily apparent upon reading the following description of an exemplaryembodiment of the present invention and upon reference to theaccompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a heavy-duty, off-road truck showingthe dump body in the lowered position and an illustrative tailgateassembly constructed in accordance with the present invention in theclosed position.

FIG. 2 is a side elevation view of the heavy-duty, off-road truck andtailgate assembly of FIG. 1 showing the dump body in the raised positionand the tailgate assembly in the open position.

FIG. 3 is a perspective view of the tailgate assembly of FIG. 1 whichalso shows the tailgate outrigger/chassis attachment.

FIG. 4 is an exploded, partial perspective view of the tailgate assemblyof FIG. 1.

FIG. 5 is a side elevation view of the tailgate of the tailgate assemblyof FIG. 1.

FIG. 6 is an end elevation view of the tailgate of the tailgate assemblyof FIG. 1.

FIG. 7 is an enlarged perspective view of the connection between one ofthe sidearms and the center-rear portion of the tailgate assembly ofFIG. 1.

While the invention will be described and disclosed in connection withcertain exemplary embodiments, it is not intended to limit the inventionto those specific embodiments. Rather it is intended to cover all suchalternative embodiments and modifications as fall within the scope ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now more particularly to FIGS. 1 and 2, an exemplaryheavy-duty, off-road truck 10 having a dump body 12 and tailgateassembly 14 constructed in accordance with the teachings of the presentinvention is shown. The truck 10 includes a chassis 16 which issupported on a plurality of tires 17 and to which the dump body 12 isattached for pivotal movement about an axis between a lowered position(FIG. 1) for receiving and transporting a load of material and a raisedposition (FIG. 2) for dumping the load. In the illustrated embodiment,the dump body 12 is moved between the lowered and raised positions byactuation of a hydraulic dump cylinder 19 carried on the chassis 16 ofthe truck 10. The dump body 12 is generally constructed of steel panelswhich define the shape of the dump body and beams which form thestructural framework for the dump body.

In the illustrated embodiment, the truck 10 is generally symmetricalabout its longitudinal axis. Accordingly, as will be appreciated, manyof the elements identified in the side views of FIGS. 1-2 havecomplementary elements arranged on the opposite side of the truck 10.For ease of references herein, the present invention will only bedescribed in connection with the side of the truck shown in FIGS. 1-2.However, it will be appreciated that in one embodiment of the inventioncomplementary elements are provided on the side of the truck that is notshown.

In this case, the dump body 12 comprises a pair of opposing sidewalls20, a front wall 22 and a floor 24. The dump body 12 further includes acanopy 26 which is integrally connected to the top end of the front wall22 and extends towards the cab of the truck 10. The illustrated tailgateassembly includes a pair of laterally spaced, parallel sidearms 28between which a center-rear portion 30 of the tailgate is supported.Each sidearm 28 is pivotally connected to a respective one of thesidewalls 20 of the dump body 12 by a pivot pin 32 so as to allow thesidearms to rotate relative to the dump body 12 between a closedposition (FIG. 1) and an open position (FIG. 2). In the closed position,the tailgate assembly 14 is in a lowered position with the center-rearportion 30 of the tailgate extending between the opposing sidewalls 20and, when being loaded, closing off the rear end of the dump body 12 asshown in FIG. 1. With the rear end of the dump body 12 closed off, thevolumetric capacity of the dump body is increased for more efficienthauling of material. In the open position, the center-rear portion 30 ofthe tailgate assembly is pivoted upward relative to the rear end of thedump body 12 so as to allow material to be dumped from the rear of thedump body 12 as shown in FIG. 2.

For rotating the tailgate assembly 14 between the closed (FIG. 1) andopen (FIG. 2) positions, the tailgate assembly 14 includes an actuatingassembly. The actuation assembly comprises, in this instance, a cable orchain 36 that is connected at one end to the sidearm 28 and at theopposing end to an outrigger 38 (FIG. 3) that is attached to the truckchassis 16. The chain 36 produces a torque on the tailgate assembly 14that rotates the tailgate assembly between the closed and open positionsas the hydraulic dump cylinder 19 pivots the dump body 12 between theraised and lowered positions.

In accordance with one important aspect of the present invention, thecenter-rear portion 30 is connected to the sidearms 28 in such a mannerto substantially improve the strength and durability of the tailgateassembly 14 as compared to prior art designs. As explained above, theconnections between the center-rear potion and the sidearms can be aweak point in the design of a tailgate assembly in that the nuts andbolts and/or welded joints holding the components together are subjectedto a substantial amount of stress that, because of their relativelysmall size and/or placement, they frequently are unable to totallywithstand. With the connection arrangement of the present invention, theoverall strength and durability of the tailgate assembly 14 is improvedby eliminating the stress on the nuts and bolts and/or welded joint.Instead, with the present invention, the nuts and bolts are used tosimply set the tailgate assembly 14 at the proper width. As a result,the width of the tailgate assembly 14 can also be adjusted much moreeasily.

To this end, as shown in FIGS. 3, 4, 6 and 7, an extended portion 40 isprovided on the free end of each of the sidearms 28. As best shown inFIG. 4, the extended portions 40 are integral with the rest of therespective sidearm 28 so that the sidearms 28 still can have a one-piececonstruction. As shown in FIGS. 3, 4, 6 and 7, the extended portions 40are bent inwardly towards each other and the center so as to definerespective connection surfaces to which the center-rear portion 30 canbe mounted. In particular, as best shown in FIG. 4, an inside surface 42of each extended portion 40 defines a connection surface against whichthe outside surface 44 of the center-rear portion 30 abuts. Thecenter-rear portion 30 still spans across substantially the entire widthof the open rear end of the dump body 12, but the extended portions 40overlie the outer surface 44 of the center-rear portion 30 adjacent tothe ends 46 thereof. Thus, any force caused by material in the dump body12 colliding against the inside surface 45 of the center-rear portion 30is transmitted from the outside surface 44 of the center-rear portiondirectly to the inside surfaces 42 of the extended portions 40 andthereby to the sidearms 28.

As compared to conventional nut and bolt or welded connectionarrangements, the extended portions 40 distribute the force over a muchlarger area thereby greatly decreasing the stress on the connections. Aswill be appreciated, the extended portions 40 should overlap thecenter-rear portion 30 an amount that allows for sufficient distributionof the force acting on the connections. For example, the extendedportions 40 can each overlap between 7-30% of the length of thecenter-rear portion 30.

Since the center-rear portion 30 is arranged inside the extended ends ofthe sidearms 28 as opposed to outside as with the conventionalconnection arrangement, the lower edge 47 of the center-rear portion 30can be arranged in closer proximity to the rear end of the dump bodyfloor 24. This helps prevent any gap between the dump body floor 24 andthe center-rear portion 30 through which material could spill.

In the illustrated embodiment, the center-rear portion 30 is securedrelative to the extended portions 40 of the sidearms by bolts 48 asshown in FIG. 4. The bolts 48 extend through corresponding openings inthe center-rear portion 30 and the extended portion 40 of the sidearm 28and are secured in place by mating washers 50 and nuts 52. In this case,a washer plate 54 is provided to help facilitate the connection betweeneach of the extended portions 40 of the sidearms 28 and the center-rearportion 30. Additionally, in this case, openings 56 are provided in thewasher plate 54 to provide access for spot welding the washer plate 54to the extended portion 40. As will be appreciated, the washer plate 54can be used in lieu of individual flat washers. However, a washer plateis not required to secure the center-rear portion 30 to the extendedportions 40 of the sidearms. Moreover, if a washer plate is provided,the openings are not required.

To allow the width of the tailgate assembly 14 to be easily adjusted,the bolt openings 58 in the extended portions 40 of the sidearms 28 canbe slotted as shown in FIG. 4. These slotted bolt openings 58 allow theposition of the center-rear portion 30 to be adjusted relative to thesidearms 28 in order to match the width of the open rear end of the dumpbody 12. Thus, there is no need to use any shims or the like,substantially easing the assembly process. As can be seen, thenuts/bolts only function to secure the center-rear portion 30 in theproper position relative to the sidearms 28 and are not subjected tostress caused by loaded material in the dump body 12 colliding with thecenter-rear portion 30.

To provide the curved sections 59 of the extended portions 40 of thesidearms 28 with additional strength, and in particular rigidity againstbending, in this instance, a support flange 60 may be attached to eachsidearm 28. As shown in FIG. 7, the support flange 60 is attached, inthis case, along an upper edge of each of the sidearms 28. The supportflange 60 extends along the upper edge of the sidearm 28 from the mainportion 62 of the sidearm through the curved section 59 and along asection of the extended portion 40. It will be appreciated that thesupport flange 60 can have configurations other than that shown in thedrawings as well as different locations.

According to a further aspect of the present invention, the center-rearportion 30 can have a configuration that allows it to be made of asingle piece without any reinforcing structures attached thereto. One ofthe more time consuming steps associated with manufacturing a tailgateassembly consists of welding reinforcing structures to the tailgatecenter-rear and sidearm portions. These reinforcing structures areneeded to help prevent lateral bending of the center-rear and sidearmportions.

As best shown in FIGS. 3-6, the illustrated center-rear portion 30 hasan outward bend or curl 64, 66 (i.e., away from the interior of the dumpbody 12) adjacent its upper edge and adjacent its lower edge. Each curl64, 66 extends along a substantial portion of the distance between thesidearms 28. Specifically, as shown in FIGS. 3 and 6, the upper curl 64extends across the entire upper edge of the center-rear portion 30 fromthe main portion 62 of one sidearm 28 to the main portion of the othersidearm. The lower curl 66 extends between respective cut-out sections67 in the lower edge of the center-rear portion 30 such that the lowercurl 66 extends approximately from the inner end of one body side wall20 to the inner end of the other body side wall. The upper and lowercurled portions 64, 66 stiffen the center-rear portion 30 againstlateral bending allowing a relatively lighter weight piece of, forexample, steel to be used while minimizing the need for any attachedreinforcing structures. Since the curls 64, 66 can be produced in thecenter-rear portion 30 using a simple metal forming operation, thetailgate assembly 14 can be manufactured much more efficiently.

As shown in FIGS. 3-5, similar bends or curls 68, 70 can also beprovided in the upper and lower edges of the main portions 62 of thesidearms 28 to provide further rigidity thereto. In this case, the curl68 at the upper edge of the sidearm 28 is curled inward towards the dumpbody 12 while the curl 70 at the lower edge of the sidearm 28 is outwardaway from the dump body 12. Both the upper and lower sidearm curls 68,70 extend along substantially the entire length of the respective mainportions 62 of the sidearms 28. Again, the curls 68, 70 in the sidearms28 can be fashioned using a simple metal forming operation. It will beappreciated that the curls 64, 66, 68, 70 in the center-rear portion 30and in the sidearms 28 can have shapes and configurations other thanthat shown in the illustrated embodiment.

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Recitation of ranges of values herein are merely intended toserve as a shorthand method of referring individually to each separatevalue falling within the range, unless otherwise indicated herein, andeach separate value is incorporated into the specification as if it wereindividually recited herein. All methods described herein can beperformed in any suitable order unless otherwise indicated herein orotherwise clearly contradicted by context. The use of any and allexamples, or exemplary language (e.g., “such as”) provided herein, isintended merely to better illuminate the invention and does not pose alimitation on the scope of the invention unless otherwise claimed. Nolanguage in the specification should be construed as indicating anynon-claimed element as essential to the practice of the invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventor for carrying out the invention. Ofcourse, variations of those preferred embodiments will become apparentto those of ordinary skill in the art upon reading the foregoingdescription. The inventor expects skilled artisans to employ suchvariations as appropriate, and the inventor intends for the invention tobe practiced otherwise than as specifically described herein.Accordingly, this invention includes all modifications and equivalentsof the subject matter recited in the claims appended hereto as permittedby applicable law. Moreover, any combination of the above-describedelements in all possible variations thereof is encompassed by theinvention unless otherwise indicated herein or otherwise clearlycontradicted by context.

What is claimed is:
 1. A tailgate assembly for a dump body, the dumpbody having a pair of opposing sidewalls and an open rear end, the dumpbody being movable relative to a chassis between a lowered transportposition and a raised dump position, the tailgate assembly comprising: apair of opposing sidearms each of which is pivotally connected to arespective sidewall of the dump body and a center-rear portion supportedbetween the opposing sidearms, the sidearms and center-rear portionbeing movable between a closed position wherein the center-rear portionspans substantially between the opposing sidewalls of the dump body andencloses the open rear end of the dump body and an open position whereinthe center-rear portion is positioned away from the open rear end of thedump body, the center-rear portion having an inside surface which facesan interior of the dump body and an opposing outside surface which facesaway from the interior of the dump body, and wherein each of thesidearms includes an extended portion at an end thereof, the extendedportions being curved inwardly toward each other in overlapping relationto at least a portion of the center-rear portion and each extendedportion being fastened to the center-rear portion with a portion of aninside surface of each of the extended portions abutting against aportion of the outside surface of the center-rear portion.
 2. Thetailgate assembly of claim 1 further including an actuating assembly formoving the sidearms and center-rear portion between the closed and openpositions as the dump body moves between the lowered, transport positionand the raised, dump position.
 3. The tailgate assembly of claim 2wherein the actuating assembly includes a link having a first endconnected to one of the sidearms and a second end that is connectable tothe chassis.
 4. The tailgate assembly of claim 1 wherein a supportflange is arranged on at least one of the sidearms so as to extendaround the curve of the respective extended portion.
 5. The tailgateassembly of claim 4 wherein the support flange is arranged on an edge ofthe sidearm.
 6. The tailgate assembly of claim 1 wherein each extendedportion is connected to the center-rear portion by at least onerespective bolt which extends through corresponding openings in thecenter-rear portion and the respective extended portion.
 7. The tailgateassembly of claim 6 wherein the opening in either the center rearportion or the respective end portion is slotted so as to allow theposition of the center-rear portion to be adjusted relative to thesidearms.
 8. The tailgate assembly of claim 1 wherein the center-rearportion has upper and lower edges extending between the sidearms, thecenter-rear portion being curled adjacent the upper edge and adjacentthe lower edge with each curl extending along a substantial portion ofthe distance between the sidearms so as to make the center-rear portionmore resistant to lateral bending.
 9. The tailgate assembly of claim 8wherein the center-rear portion does not have any structures attachedthereto for reinforcing the center-rear portion against lateral bending.10. The tailgate assembly according to claim 8 wherein the curls areaway from the interior of the dump body.
 11. The tailgate assembly ofclaim 1 wherein the center rear portion has a curl along an edge thereofwhich extends a substantial portion of the distance between thesidearms.
 12. The tailgate assembly of claim 11 wherein the center rearportion has a curl along both an upper and a lower edge thereof each ofwhich extends a substantial portion of the distance between thesidearms.
 13. The tailgate assembly of claim 1 wherein at least one ofthe sidearms has a curl along an edge thereof.
 14. The tailgate assemblyof claim 13 wherein the sidearm has curls along both an upper and alower edge thereof.
 15. The tailgate assembly of claim 14 wherein bothsidearms have curls along both an upper and a lower edge thereof. 16.The tailgate assembly of claim 14 wherein one of the curls extendstowards the dump body and the other curl extends away from the dumpbody.
 17. The tailgate assembly of claim 1 wherein the extended portionof each sidearm is integral with the remainder of the respectivesidearm.
 18. A tailgate assembly for a dump body, the dump body having apair of opposing sidewalls and an open rear end, the dump body beingmovable relative to a chassis between a lowered transport position and araised dump position, the tailgate assembly comprising: a pair ofopposing sidearms each of which is pivotally connected to a respectivesidewall of the dump body at least one of the sidearms having a curlalong a substantial portion of an edge thereof, a center-rear portionsupported between the sidearms, and an actuating assembly for moving thesidearms and center-rear portion between a closed position wherein thecenter-rear portion spans substantially between the opposing sidewallsof the dump body and encloses the open rear end of the dump body and anopen position wherein the center-rear portion is positioned away fromthe open rear end of the dump body, the center-rear portion having upperand lower edges extending between the sidearms, the center-rear portionbeing curled away from the interior of the dump body adjacent the upperedge and adjacent the lower edge with each curl extending along asubstantial portion of the distance between the sidearms so as to makethe center-rear portion more resistant to lateral bending and whereinthe center-rear portion does not have any structures attached theretofor reinforcing the center-rear portion against lateral bending.
 19. Thetailgate assembly of claim 18 wherein the sidearm has curls along bothan upper and a lower edge thereof.
 20. The tailgate assembly of claim 19wherein both sidearms have curls along both an upper and a lower edgethereof.
 21. The tailgate assembly of claim 19 wherein one of the curlsextends towards the dump body and the other curl extends away from thedump body.
 22. A tailgate assembly for a dump body, the dump body havinga pair of opposing sidewalls and an open rear end, the dump body beingmovable relative to a chassis between a lowered transport position and araised dump position, the tailgate assembly comprising: a pair ofopposing sidearms each of which is pivotally connected to a respectivesidewall of the dump body and a center-rear portion supported betweenthe opposing sidearms, the sidearms and center-rear portion beingmovable between a closed position wherein the center-rear portion spanssubstantially between the opposing sidewalls of the dump body andencloses the open rear end of the dump body and an open position whereinthe center-rear portion is positioned away from the open rear end of thedump body, the center-rear portion having an inside surface which facesan interior of the dump body and an opposing outside surface which facesaway from the interior of the dump body, and wherein each of thesidearms includes an extended portion at an end thereof, the extendedportions being curved inwardly toward each other in overlapping relationto at least a portion of the center-rear portion and each extendedportion being fastened to the center-rear portion with a portion of aninside surface of each of the extended portions abutting against aportion of the outside surface of the center-rear portion, each of theextended portions overlapping a majority of a respective outer edge ofthe center-rear portion.
 23. The tailgate assembly of claim 22 whereineach extended portion is connected to the center-rear portion by atleast one respective bolt which extends through corresponding openingsin the center-rear portion and the respective extended portion.
 24. Thetailgate assembly of claim 23 wherein the opening in either thecenter-rear portion or the respective end portion is slotted so as toallow the position of the center-rear portion to be adjusted relative tothe sidearms.
 25. The tailgate assembly of claim 22 wherein thecenter-rear portion has upper and lower edges extending between thesidearms, the center-rear portion being curled adjacent the upper edgeand adjacent the lower edge with each curl extending along a substantialportion of the distance between the sidearms so as to make thecenter-rear portion more resistant to lateral bending.
 26. The tailgateassembly of claim 22 wherein a support flange is arranged on at leastone of the sidearms so as to extend around the curve of the respectiveextended portion.
 27. The tailgate assembly of claim 22 wherein theextended portion of each sidearm is integral with the remainder of therespective sidearm.